1. Field of the Invention
The present invention relates to fluid system testing apparatus and methods. More particularly, the present invention relates to apparatus and methods for testing fluid systems for leakage.
2. Prior Art
Some prior methods use for testing fluid systems for leakage are described in U.S. Pat. No. 4,013,537 to Victor, the disclosure of which is incorporated by reference herein. In addition to the shortcomings discussed in the Victor disclosure, additional problems exist in the prior systems, including the Victor device and method.
First, for fluid systems having relatively small fluid volumes, the relatively short elapsed time of the typical "pressure drop per time" test period makes it difficult to obtain accurate measurements of leakage quantity. Additionally, smaller fluid volume increases the significance of the concurrent leakage during the testing period. Other drawbacks of prior fluid testing methods include the inaccuracies created by a defective or non-precision pressure gauge and operator error in manually reducing the system fluid pressure to equal the pressure measured during the timing phase of the testing procedure.
In some previous leakage testing methods, the system fluid is set to a predetermined pressure, and measurements are made after the fluid pressure has dropped to a lower level. These methods typically require the use of fluctuating pressure to obtain leakage measurements. Accordingly, leakage measurements are made relative to an average fluid pressure. Because the quantity of fluid passing through a leakage orifice decreases as the fluid pressure decreases, further inaccuracies in the leakage quantity measurement are introduced.